iAd ties into e-commerce because of one key advertising advancement Apple is looking to introduce: cross-device retargeting. Cross-device retargeting is of most benefit to retailers: if a customer spends some time looking at a dress on an iPad app and decides not to buy it, that same retailer can then “retarget” them the next time they pick up their iPhone with an ad displaying an image of that same dress, options to by it, or with directions to the store.

Competitors are also attempting to build cross-device retargeting solutions, but Apple’s advantage over its rivals is that Apple users spend 87% of the time on connected devices within apps. That’s a lot of opportunities to serve ads, and all with Apple’s industry-leading data targeting. It knows a lot about its users and their habits, thanks to the information they supply when they register for Apple ID.

What’s more, for marketers, Apple Pay is integrated into Apple Passbook: meaning brands have an incredibly powerful platform to send consumers offers. Powerful because it’s easier to use your phone to redeem offers and then purchase goods, rather than redeeming offers with your phone and paying by another method — that’s the kind of complication that could put a consumer off buying your brand and being tempted by another in-store.

iBeacons

An Apple iOS 7 slide mentioning iBeacon.GigaOM

Keeping on the in-store theme: millions of low-powered beacons are being installed by retailers across the globe, allowing marketers to target consumers on their mobiles with advertising and offers, enticing them to come into the store they’re just a few feet away from.

These iBeacons help Apple “close the loop” of mobile retailing. Apple is doing incredible work in the online and mobile space for brands through iAd and apps: iBeacons helps bring that online magic to the bricks and mortar location.

iTunes

Let us not forget that Apple already has a huge e-commerce business of its own, without having to tap into other companies’ ecosystems.

With an annual run-rate of more than $16 billion a year in digital e-commerce sales, Apple is already an e-commerce titan bigger than the likes of Zappos, which last reported annual revenues $1 billion (although they're still both a long way behind Alibaba, Amazon or eBay).

The Big Picture

Products like the Apple Watch and latest iPhones and iPads are always going to make headlines for Apple. But that's not the way Apple's business partners see the company. For them, these devices are simply the physical platforms that tie customers into a huge e-commerce ecosystem that links Apple's own online store, offers, ads apps, and payments into one giant loop — all of which have huge revenue-earning potential.